NEWEST NEW ENERGY STORAGE

Breakthrough in Energy Storage: Isentropic Energy; Isentropic Energy’s pumped-heat electrical energy storage could disrupt the large-scale electrical energy storage market.
Eric Wesoff, February 23, 2010 (Greentech Media)

"…Today, the only economical method of storing energy at a large scale is pumped hydro…[which is] almost all large-scale electricity storage…or Compressed Air Energy Storage (CAES). Unfortunately, both…[are unweildy and costly]…

"…[T]he technologies that are most likely to reach commercialization in the near term are [CAES and] Lithium-ion batteries …[T]he cost of large-format Lithium-ion (for electric vehicles and utility-scale storage) [coulc] drop to $250 per kilowatt-hour…[But] Jonathan Howes, the Chief Technical Officer of U.K. start-up Isentropic Energy…is claiming large-scale storage costs that are an order of magnitude lower than Lithium-ion batteries or other stored energy technologies -- $55 per kilowatt-hour currently, with a path to get down to $8 per kilowatt-hour."

From Greentech Media (click to enlarge)

"Isentropic's technology is compact, has no geographical constraints and claims a round-trip efficiency of 72 to 80 percent…Isentropic's Pumped Heat Electricity Storage (PHES) system is based on the First Ericcson cycle and uses a heat pump to store electricity in thermal form. The storage system uses two large containers of gravel, one hot (500C) and one cold (-150C). Electrical power is input to the machine which compresses/expands air to 500C on the hot side and -150C on the cold side. The air is passed through the two piles of gravel, where it gives up its heat/cold to the gravel. In order to regenerate the electricity, the cycle is reversed. The temperature difference is used to run the system as a heat engine.

"…[Isentropic] claims that its reversible engine/heat-pump boasts three critical features…[1] Very high round-trip efficiency -- 72 to 80 percent…[2] High reversibility -- the machine works as both an engine and heat pump…[I]f it first turns electricity into a temperature difference, it can then regenerate most of the electricity from the temperature difference…[3] Gas cycle machine -- no use of damaging refrigerants, chemicals, or water…"

From Greentech Media (click to enlarge)

"Isentropic's innovations include using aircraft engineering techniques to reduce piston weight and cost, designing new valving to eliminate pressure losses, and using a new sealing technology.

"The design is intended for "small utility scale." Howes is targeting 2-megawatt 8-hour systems (16MW-hrs), although he claims that the systems can scale up and down. The firm is in the early stage and has built a "proof of ignorance prototype," followed by a technology demonstrator. Design of prototype three is now completed and has been built to demonstrate reliability…"